Apparatus and method for forming stranded cables



APPARATUS AND METHOD FOR FORMING STRANDED CABLES Filed May 7, 1962 Oct. 15, 1963 G. J. NANCE ETAL 2 Sheets-Sheet 1 INVENTORJ w |lwll a |*l| 4 .J 4 a a A A A0 [7w A0 WM 9 2 Q BY W A TTOR/VE Oct. 15, 1963 G. J. NANCE ETAL APPARATUS AND METHOD FOR FORMING STRANDED CABLES 2 Sheets-Sheet 2 Filed May 7, 1962 INVENTORJ United States Patent 3,106,815 APPARATUS AND METHOD FOR FORMING STRANDED CABLES Granval J. Nance and Edward G. McDonald, Houston, Tex., asslgnors, by mesne assignments, to Vector Cable Company, Houston, Tex., a corporation of Texas Filed May 7, 1962., Ser. No. 192,897 8 Claims. (Cl. 5713) This invention relates to apparatus and methods for forming electrical cable cores, particularly cable cores for well logging electrical cables which include insulated electrical conductors embedded in a core member.

Heretofore, one type of cable core assembly, known as a seven conductor core assembly, has been proposed in which six outer conductors are spirally embedded in core matrix, the core matrix containing the seventh and centrally located inner conductor. To form this core, a core matrix and the outer conductors are passed through a stationary closing die, the outer conductors being supplied from a rotating frame so as to be laid spirally on and about the core matrix and embedded into the outer surface of the core matrix by the die. The conductors are generally spaced from one another in the closing die by intervening, fibrous threads also supplied from the frame, the threads being disposed intermediate the conductors and made a part of the core assembly.

To provide a finished cable, a sheath of material is applied to the core assembly and combines with the core matrix to provide a substantially monolithic, cylindrically shaped embedding mass in which the conductors are separated from one another by the threads. The sheathed assembly is then cabled with inner and outer load supporting armor wires in a well-known manner.

It is desirable that the outer sheath and core matrix be constructed of material which is semi-conductive so as to reduce or avoid capacitive cross-talk effects upon electrical signals transmitted via the conductors. However, the conductor spacing threads or strings tend to disrupt the conductivity of the sheathing material. Furthermore, the sheath about the threads does not fully saturate the void spaces in and about the threads. Hence, when a cable as described above, is utilized, for instance, to support a well logging tool in a well bore and the sheathed core assembly is subjected to heavy compressive and tensile stresses, the material of the sheathed core assembly exudes into the void spaces and adversely affects the length stability of the cable and also adversely aifects the distribution of stresses in the armor wires.

Consequently, an object of the present invention is to provide new and improved apparatus for forming a cable core assembly in which the threads are eliminated.

Another object of the present invention is to provide new and improved apparatus for forming cable core assemblies in which there is provided a novel, rotatably mounted closing die.

Still another object of the present invention is to provide new and improved apparatus of the type described having a rotatable closing die with self-adjusting spacers wherein the spacers are shiftable relative to the die for forming core assemblies with spiraled conductors.

Still another object of the present invention is to provide new and improved methods for forming core assemblies for well logging cables.

These objects and others are attained in the novel apparatus and methods herein described in which the apparatus includes, generally, a conventional rotating frame which carries conductor supply spools. A closing die is also rotatably mounted adjacent the frame, conveniently as a part thereof, so that the frame and die rotate about a common central axis. A central, tubular mast or casing permanently embedded spacing extends axially through the frame and provides a passage way through which a core matrix member can be axially fed along the common rotation axis to the closing die while the outer conductors from the supply spools on the frame are also supplied to the closing die. The closing die is provided with loosely mounted spacer elements which separate the outer conductors from one another while passing through the die. Rotation of the frame (and supply spools) causes the conductors to be laid spirally along and about the core matrix member, the spacing elements adjusting to the spiral entry of the conductors into the closing die. The closing die embeds the outer conductors into the pliable core matrix material, thereby causing extrusion of the material in between the conductors. The resulting core assembly is pulled from the closing die and collected on a power driven spool.

Subsequently, the spooled core assembly can be processed through an extrusion die where additional matrix material under pressure is applied about and in between the spiraled conductors to provide a cylindricallyshaped, sheathed assembly. In this process, the spiraled, outer conductors are firmly and completely encased, and the spaces between contiguous outer conductors are compactly filled by the sheathing and core matrix material. Hence, no spacing element such as threads previously used remains in the core assembly. The sheathed assembly may then be cabled with the inner and outer load supporting armor wires in a conventional manner.

The process of the present invention includes the steps of supplying a core matrix and outer conductors to a closing die, rotating the closing die and spiraling the conductors about the core matrix, and spacing the conductors from one another in the die while the die is rotating.

In the accompanying drawings which illustrate the invention,

FIG. 1 is a view in perspective of an armored well logging cable, successive components being broken away to better illustrate details of the cable construction;

FIG. 2 is a schematic representation of a portion of apparatus for forming an armored well logging cable;

FIG. 3 is a schematic but more detailed View on a larger scale showing a system for forming core assemblies in accordance with the present invention;

FIG. 4 is a view of the left-hand end of the closing die of the present invention in operation taken substantially along line 4-4 of FIG. 3, but with the core matrix omitted to clarify the illustration of the outer conductors and spacers in the closing die;

FIG. 5 is a section taken substantially along line 5-5 of FIG. 4, the core matrix being shown in dot-and-dash lines;

FIG. 6 is a transverse section taken substantially along line 66 of FIG. 5, but showing the core matrix in position.

The cable illustrated in FIG. 1 consists of a central, axial conductor It) which includes woven wires 11 encased in a suitable insulation material such as Teflon. Conductor 10 is centrally embedded in core matrix member 12. Spirally wound about member 12 are outer conductors 13, each constructed similar to conductor 10. The spiraled conductors 13 are completely encased by additional embedding material 14 which joins with the matrix material 12 to provide a monolithic sheathing 15 having a generally cylindrical outer surface. Sheathing 15 (comprised of core member 12 and embedding material 14) preferably is formed of an extrudable, semi-conductive, oil and gas resistant elastomer which cures to a hard, flexible, relatively incompressible form and maintains its physical properties at borehole temperatures and pressures. For instance, the acrylonitrile-butadiene rubber known commercially as Hycar is well adapted for this purpose. It will be noted that the sheathing 15, as

J) integrally connected in the finished cable, has hour-glass portions 16 extending about the conductors 13 so that the spiral conductors are firmly and uniformly supported and separated from each other and from the central conductor 1% by the sheathing material. Received about sheathing 15 are the oppositely-spiraled armor wires 17 and 18.

An apparatus for forming part of the cable is schematically represented in FIG. 2. This apparatus includes a spool 19 from which the axial conductor 19 is supplied. Conductor 1%) is subjected to an extruding device 20 which applies uncured, semi-conductor core material thereto to form core matrix member 12 having a generally cylindrical form. Matrix member 12 is then fed axially through a closing die, represented generally at 21. 'Into this die are also fed the insulated outer conductors 13. Conductors 13 are supplied from spools 22 (six illustrated) which spools are mounted in a well-known manner upon a rotatable frame (to be described). The frame and closing die rotate about a common axis and the conductors are embedded in the core member in passing through the closing die. The core assembly, which includes matrix member 12 and conductors 13, is next fed through a second extruding device 23 wherein uncured outer sheathing material 14 is applied under pressure to cause the matrix material to extrude about the outer parts of spiraled conductors 13 and merge with inner core member 12. Next, this assembly is subjected to curing action in an oven 24 which forms the monolithic sheathing 15 firmly embedding the conductors therein. Finally, the inner and outer armor strands 17 and 18 are applied by known means (not shown) and the finished cable stored upon the reel or spool 25.

While the above process is illustrated in continuous form, it, generally, is the practice to form the cable from a succession of independent steps. For example, the core matrix 12 is made first and spooled on a drum. The core matrix and conductors 13 are next combined to form the core assembly which can be spooled on a drum. Next, the core assembly can be subjected to the extruding apparatus 23 and oven 24. This sub-assembly can also be spooled on a drum so that the armor Wires may be applied in a final operation.

FIG. 3 is a more detailed disclosure of the present invention. A rotatable frame F mounts outer conductorsupplying spools 22. The frame F includes a central tubular mast or casing 26 and longitudinally spaced, wheellike supporting parts 27 and 28. Between parts 27 and 28 cradles 29 are pivotally mounted and carry part of spools 22. At the left end of the frame is a wheel 30 having peripheral spur teeth 31 meshing with driving pinion 32 operated by a suitable motor 33. Cradles 34 are pivotally mounted between part 28 and wheel 30 and carry others of spools 22. Wheel-like parts 27 and 28 and, therefore, the entire spool mounting frame, are rotatably supported on rollers 35. Axial mast 26 terminates at its right end in a fixture 38 having a left end wall 39 provided with circularly arranged conductor apertures 41). Right-hand end wall 41 of the fixture rigidly mounts the closing die 21. Since fixture 38 and the closing die 21 are rigidly connected to the spool-mounting frame and mast 26, these parts rotate together under the influence of motor 33.

Closing die 21, constituting a principal feature of the present invention, is shown in enlarged scale in FIGS. 4, 5 and 6. The die 21 consists of a body part 46 having a Venturi-shaped aperture 47 extending therethrough. Loosely received within aperture 47 are a plurality, in this instance, six, wire-like spacer elements 48. Spacer elements 48 lie along the inner wall of the die aperture and have angled extremities 49 and 50, respectively, overlying the end walls 51 and 52 of body 46. Outer conductors 13, as shown in FIG. 3, are fed from spools 22 through apertures (not shown) in the frame and apertures 40 in end wall 39 in fixture 38 into the spaces between the spacer elements 48 in the closing die. Cylindrically shaped core matrix member 12 is also supplied through the interior of the mast 26 and axially through fixture 33 and closing die 21. Spacer elements 48 are free to assume inclinations conforming to those of the conductors 13. Also, these spacer elements may shift circumferentially, as required, to conform to variations in thickness of the conductors 13.

The small or closing end of the die aperture 47 is proportioned so as to snugly receive all of the outer conductors 13 and spacer elements 48 and to partially embed the outer conductors 13 (which are of greater diameter than the spacer elements), in the surface of inner matrix or core member 14 (see FIG. 6). This, in turn, causes the matrix material of the core member 12 to extrude radially into ridges, substantially filling the spaces between contiguous conductors 13 and beneath spacer elements 43. The outer conductors 13 will be laid spirally and equally spaced upon the surface of core member 12, as indicated at 54- in FIG. 5, by rotation of the conductors about the non-rotating core member 14. Of course, since the spacer elements are retained by the closing die, only solid matrix material remains exposed between conductors 13 on the downstream side of the closing die.

A draw-01f spool 56, driven under power means (not shown), is used to pull the core member 12 and conductors 13 through the die 21 and collect the core assembly for subsequent processing into cable.

In operation, the core member 12 is fed from a supply spool 2% through the mast 26, fixture 38, and die 21.

Conductors 13 are hand fed from the supply spools 22 on the frame and pulled through die '21, each of the conductors being spaced from one another by spacer elements 48. The ends of the core member 12 and conductors 13 are connected to draw-off spool 56. Spool 56 is rotated to pull the core assembly members 12 and conductors 13 through the closing die 21 while the frame F and die rotate so as to spirally lay conductors 13 about core member 12. Spacer elements 48 (which rotate with the die) adjust to the spiral angles and thicknesses of the conductors.

The method of the present invention of forming core assemblies in a closing die includes the steps of linearly feeding a core member to the closing die, spirally laying conductors along and about the core member while pulling the core member and conductors through the die and rotating the closing die, and spacing the conductors from one another as the core member and conductors pass through the rotating closing die.

The exact form and shape of the closing die as well as the spacer elements, the material and construction of the core member and spiraled conductors, and the number of and feed angles of the spiral conductors may be modified in various ways as will occur to those skilled in the art. The exclusive use of all modifications as come within the scope of the appended claims is contemplated.

We claim:

1. Apparatus for forming core assemblies for cables comprising a rotatably mounted closing die, means for supplying a core member axially through said die, a frame rotatably mounted coaxially With respect to said die, means to supply a plurality of conductors from said frame through said die, a draw-off spool for receiving the core assembly disposed beyond said die and said frame, spacer means in the orifice of said die for separating contiguous conductors from one another, said spacer means being loosely mounted on said die for self adjustment, and powering means for rotating said die, said frame, and said draw-off spool.

2. Apparatus for forming core assemblies for cables comprising a rotatably mounted closing die, means for supplying a core member axially through said die, a frame rotatably mounted coaxially with respect to said die, means to supply a plurality of conductors from said frame through said die, said die being proportioned to cause substantial indentation of said conductors into the surface of said core member and extrusion of said core member at least in part about said conductors, a draw oil spool for receiving the core assembly disposed beyond said die and said frame, spacer means in the orifice of said die for separating contiguous conductors from one another, and powering means for rotating said die, said frame, and said draw-off spool.

3. Apparatus for forming core assemblies for cables comprising a rotatably mounted closing die, means for supplying a core member axially through said die, a frame rotatably mounted co-axially with respect to said die, means to supply a plurality of conductors from said frame through said die, said die being proportioned to cause substantial indentation of the conductors into the surface of said core member and extrusion of said core member at least in part about said conductors, a draw-off spool for receiving the core assembly disposed beyond said die and said frame, spacer means in the orifice of said die for separating contiguous conductors from one another, said spacer means comprised of wire-like elements mounted on said die for separating said conductors in passage through said die, and powering means for rotating said die, said frame, and said draw-off spool.

4-. Apparatus for forming core assemblies for cables comprising a rotatably mounted closing idie, means for supplying a core member axially through said die, a frame rotatably mounted coaxially with respect to said die, means to supply a plurality of conductors from said frame through said die, said die being proportioned to cause substantial indentation of said conductors into the surface of said core member and extrusion of said core member at least in part about said conductors, a draw-off spool for receiving the core assembly disposed beyond said die and said frame, spacer means in the orifice of said die for separating contiguous conductors from one another, said spacer means comprised of wire-like elements mounted on said die for separating said conductors in passage through said die, said wire-like elements being loosely mounted on the wall of said die and traversing substantially the entire space between contiguous conductors and being of less thickness radially of said die than said conductors whereby portions of said core member are extruded into spiral ridges between said conductors, and powering means for rotating said die, said frame, and said draw-off spool.

5. Apparatus for forming stranded cables comprising a closing die mounted for rotation about its axis, means for feeding a central core member axially through said die, a frame rotatably mounted coaxially with respect to said die, conductor storing spools mounted on said frame at regular intervals about the axis thereof, means for directing conductors from said spools spirally about said core member, spacer elements in said die for positioning said conductors relative to one another, said spacer elements circumferentially traversing substantially the entire space between contiguous conductors, said die being proportioned to snugly receive said conductors and core memberto cause extrusion of said core member into ridges between said conductors, means for rotating said die, said frame, and said feeding means, and means for pulling said conductors and core member through said die.

6. Apparatus for forming a core assembly for cables comprising: a rotatably mounted closing die; means for providing a core member to said die; means for providing a plurality of conductors and spirally laying said conductors about said core member; means for pulling said conductors and core members through said die; said die having a closing orifice sized relative to said conductors and core members to embed said conductors into said core member; and means extending through said die orifice and rotatable with said die to space said conductors from one another.

7. The method of forming core assemblies in a closing die comprising the steps of linearly feeding a core member to the closing die, spirally laying conductors along and about said core member while pulling the core member and conductors through the die and rotating the closing die, the die serving to compress said conductors and core member into a compact unit, and separating said conductors from one another and maintaining the separation between said conductions as the core member and conductors pass through the closing die.

8. The method of forming a core assembly comprising the steps of:

spirally winding a plurality of conductors about a core member having a deformable covering and maintaining-a separation between contiguous conductors, and

compressing said conductors into said core'member while maintaining the separation between contiguous conductors.

References Cited in the file of this patent UNITED STATES PATENTS 2,105,338 Sunderland Jan. 11, 1938 a 2,156,652 Harris May 2, 1939 2,427,507 Powell Sept. 16, 1947 2,857,731 Simcoe Oct. 28, 1958 FOREIGN PATENTS 647,802 Great Britain Dec. 20, 1950 

1. APPARATUS FOR FORMING CORE ASSEMBLIES FOR CABLES COMPRISING A ROTATABLY MOUNTED CLOSING DIE, MEANS FOR SUPPLYING A CORE MEMBER AXIALLY THROUGH SAID DIE, A FRAME ROTATABLY MOUNTED COAXIALLY WITH RESPECT TO SAID DIE, MEANS TO SUPPLY A PLURALITY OF CONDUCTORS FROM SAID FRAME THROUGH SAID DIE, A DRAW-OFF SPOOL FOR RECEIVING THE CORE ASSEMBLY DISPOSED BEYOND SAID DIE AND SAID FRAME, SPACER MEANS IN THE ORIFICE OF SAID DIE FOR SEPARATING CONTIGUOUS CONDUCTORS FROM ONE ANOTHER, SAID SPACER MEANS BEING LOOSELY MOUNTED ON SAID DIE FOR SELF ADJUSTMENT, AND POWERING MEANS FOR ROTATING SAID DIE, SAID FRAME, AND SAID DRAW-OFF SPOOL. 